Wednesday, April 23, 2008

This look into AMD's 3 core try came about after a personal comment by Steve Gibson on Security Now! podcast with Leo Laporte, where Steve was unimpressed with the performance of a more expensive quad core processor over a less expensive and faster 2 core.

Keeping in mind that Phenom X3 is actually not that much different from Phenom X4, the most interesting thing about it is the price. After a lot of hesitation, AMD decided to set the following official prices:

So, triple-core Phenom X3 family is positioned as something in-between quad-core Phenom X4 and dual-core Athlon 64 X2. As a result, the new processors fit logically into AMD’s product map and become competitors to Wolfdale family of dual-core Intel Core 2 Duo processors, which prices were reduced this past Monday.

But will three cores of the new Phenom X3 be able to compete successfully against two Wolfdale cores? Our test session will try to answer this question. But before we move on to the results, let’s take a closer look at the triple-core processor sample we got into our lab this time.

The CPU features three L2 caches (one per each core), each 512KB big and a shared 2MB L3 cache. The built in North Bridge works at 1.8GHz frequency and supports dual-channel DDR2 SDRAM that can work in Ganged or Unganged mode. So, the CPU uses 1800MHz HyperTransport 3.0 bus, however, nevertheless, it is compatible not only with Socket AM2+ but also with older Socket AM2 mainboards.

In this respect, it is not at all surprising, that Phenom X3 loses to Core 2 Duo processors even to the cheapestE7200 and E6550 models. So it turns out that in a wide range of tasks, during regular, not any specific type of work, even three cores with K10 micro-architecture cannot compete successfully against two cores with Core micro-architecture. And the main problem with Phenom processors is, probably, their low clock frequencies.

However, let’s not draw any hasty conclusions and see how the new Phenom X3 perform in different types of applications.===================================================================Gaming Results Seem Even Worse.===================================================================3D Games

Before we move on to the gaming performance graphs we would like to remind you that to test processor performance in games we use low resolution of 1024x768. this low resolution allows us to focus on the “gaming” CPU performance and eliminate the GPU influence on the results, as the performance of this particular component is the primary determinative in real games.

The performance of Phenom X3 may differ in different games, but nevertheless, we can single out two types of behavior this processor demonstrates in gaming applications. In games, which performance is not very scalable when we have more than two processor cores (in other words, those that do not fully support quad-core processors), Phenom X3 demonstrates poor results. New triple-core processors lose to Athlon 64 X2 6400+, not to mention Intel processors in Quake 4, Half Life 2 Episode Two, and, strangely enough, Crysis.

However, there is also another group of games including Unreal Tournament 3, World in Conflict and Lost Planet: Extreme Condition. Performance in these games depends a lot on the number of available computational cores that is why the new Phenom X3 processors do not look that bad here. At least they do not yield to the top Athlon 64 X2 and sometimes are even capable of racing against Core 2 Duo CPUs not only from the previous generation, but also the new Core 2 Duo E7200.===================================================================Overclocking Gotcha===================================================================I would like to point out that Phenom X3 8750 processor we had at our disposal, just like other CPUs from the same family, features a locked clock frequency multiplier. That is why they should be overclocked by raising the clock generator frequency. This is not as easy to accomplish as we wish. The thing is that as we have already mentioned in our special article, this frequency is tied up not only to the resulting CPU frequency, but also to the frequency of the built-in North Bridge, memory and HyperTransport 3.0 bus. That is why when you increase the clock generator frequency, you should remember to reduce the corresponding coefficients and dividers forming the North Bridge, HyperTransport and DDR2 SDRAM frequencies.

For example, by raising the processor Vcore to 1.45V we could increase the clock generator frequency to 260MHz from the default 200MHz without losing stability. However, the North Bridge and HyperTrasnport frequency multipliers has to be set at 7x instead of the nominal 9x, thus keeping the corresponding frequencies close to their nominal values.

In this case Phenom X3 8750 processors overclocked to 3.1GHz frequency and remained absolutely stable. We tested stability with a one-hour run of prime 25.5 utility. To dissipate the heat from the overclocked processor we used Scythe Mugen (Infinity) air cooler.

I would like to say that 3.1GHz frequency is the best result for a K10 based processor that we managed to obtain in our lab so far. Therefore, we can hope that Phenom X3 processors are more overclocking-friendly than their quad-core fellows. However, we will be able to draw final conclusions only once we collect more data from the tests of more than one processor sample.===================================================================Power Consumption===================================================================As we have expected, triple-core processors turned out more economical than their quad-core counterparts thanks to fewer cores. Besides, they boast lower power consumption than dual-core Athlon 64 X2 thanks to not very high clock speeds. However, from the economical standpoint new Phenom X3 family still fails to compete with Intel processors.===================================================================The Bottom Line===================================================================Conclusion

AMD Phenom X3 is definitely a very interesting processor. At least since it is the industry’s first CPU with triple-core sign and monolithic organization. And although it is our first experience with a non-standard processor like that, it didn’t cause any issues when working in a convention hardware and software environment. This CPU is fully compatible with the existing infrastructure, which indicates that AMD chose the right strategy in putting the defective quad-core Phenom X4 to good use.

As for the consumer qualities and marketing future of the new processor, the things are not as clear here. All major problems typical of processors on K10 micro-architecture found their way into triple-core solutions, too. That is why Phenom X3 processors, just like Phenom X4 lack clock speed so badly. However, they are still in a little better situation than quad-core processors, because AMD positions them as competitors to Intel’s dual-core Core 2 Duo.

However, Core 2 Duo and Phenom X3 do not always show us an interesting race. We only see it in applications where performance scales well for more than two cores. Unfortunately, there are very few applications like that, so in most cases Phenom X3 loses to Intel processors from the same price range. Still, these applications do exist and include final rendering tasks, some video processing and encoding tasks, and a few others.

So, we have to state that another AMD initiative has not too many chances to succeed. Phenom X3 may become a great niche product, however, they will hardly get very popular. Youngest Intel processors fro Wolfdale family priced at the same level offer higher average performance, lower heat dissipation and power consumption and much better overclocking potential. AMD, however, will hardly dare drop the Phenom X3 prices much lower, because they use a monolithic quad-core die, which is pretty expensive to make. To be fair, I would like to add that if AMD decided to lower the prices even more, Phenom X3 may become a worthy alternative to Core 2 Duo E4000 and Pentium Dual Core.

In conclusion I would like to say that Phenom X3 can not always be recommended as a suitable upgrade for the Socket AM2 systems. The thing is that top dual-core Athlon 64 X2 processors can offer better performance, although with higher heat dissipation.

So, Phenom X3 will hardly become a bestseller. It will most likely find its users, but there are still too many reservations to be made with not too many significant advantages.

Full review at Site Listed above, needless to say, interesting reading.

About Me

I started in computing selling the TRS-80 many years ago in the early 80's and got hooked when I bought my own Coco (Color Computer). I've had a computer ever since.
I write short SF stories and Linux/OpenSource articles. I'm on Twitter as: http://twitter.com/ErnieMLopez/